Forecasting for the next three days, the Met department said that daytime temperatures may rise to 38ºC-40ºC.
According to an advisory issued by Assistant Meteorologist Ghulam Hussain Channa, sea breezes would not blow during the daytime, however, would likely resume in the evening.
"North and northwest hot and dry winds will affect the city during the heatwave," the assistant meteorologist added.
Read more: PMD issues heatwave alert for Karachi
According to PMD's spokesperson Sardar Sarfraz, humidity is likely to increase by 60 per cent during the day, while the southwest winds of the sea would be blocked for 72 hours. There was no possibility of a heatwave, he added.
The PMD further advised citizens to drink more water and to avoid direct exposure to the sunlight from 11am to 4pm to reduce the risk of heatstrokes.
The department added that on April 21, sea breezes were affected for a short while causing northern winds to blow however, they were later restored.
The port city recorded a maximum of 35.1ºC and a minimum of 26.5ºC on April 21, according to the Meteorological Department.